3．2．2 Compare and Analyze比较与分析
The conversion of mechanical energy to heat is by no means new to us．We are also familiar with other transformations of energy．①Chemical energy is converted into heat when fuel burns．Electrical energy is transformed into heat and light in electrical lamps and electrical stoves．Radiant energy turns into heat when sunlight strikes an object which absorbs it．“All contradictory things are interconnected; not only do they coexist in a single entity in given conditions，but in other given conditions，they also transform themselves into each other．” In a word，all energies may be converted from one form into another and what is more，they all can transform into heat by themselves．Heat is an energy of irregular motion of particles in a substance; at ordinary temperature it is less usable than any of the other energies．
However，at high temperatures heat energy may be converted into energy of more usable forms．②Different kinds of machines have been made to convert heat into mechanical energy．③Diesel and gasoline engines are designed to convert heat④that is developed by the burning of fuel into mechanical energy for running tractors，trucks，and cars．⑤The mechanical energy is converted from heat energy by steam turbine generators．And the generators，in turn，convert the mechanical energy into electrical energy．All these transformations are taking place every minute and everywhere in our daily life and production．
机械能转换为热能对我们而言一点也不生疏。我们也熟悉其他的能量转换形式。①燃料燃烧时，化学能就转换成热能。在电灯及电炉中，电能转换为光能和热能。太阳光照到吸收光的物体上时，辐射能就转换为热能。“一切矛盾着的东西都互相联系着，不但在一定的条件之下共处于一个统一体中，而且在一定条件之下互相转化。”总而言之，一切能都可以从一种形式转换成另一种形式，并且它们自己都能转换成热能。热能是物质内的微粒无规则运动所产生的能量，在常温下它比其他各种能的用处都小。
然而在高温下，热能可转换成更有用的能量。②人们已经制造出把热能转换为机械能的各种机器。③柴油发动机和汽油发动机被设计用来把④燃烧燃料产生的热能转换成机械能，用来开动拖拉机、卡车和汽车。⑤蒸汽涡轮机把热能转换为机械能，使发电机运转。而发电机又把机械能转换为电能。这些能量转换在我们的日常生活和生产中时时处处都在发生着。
Notes:①The original passive sentence is translated into an active-voice Chinese sentence．The original subject is retained in the Chinese sentence while the verb is used in the active voice．This is the main technique used to translate most of the passive-voice sentences in this passage．
②The original passive-voice sentence is translated into an active-voice sentence by converting the original subject into an object and by adding a new subject人们which is a pronoun of general-reference．
③The main clause of the original English sentence is in passive voice．It is translated into a passivevoice Chinese sentence by using被which is a typical marker of passive structure in Chinese．
④This attributive clause is also in passive voice．Since it introduces the agent of the action by using“by…”structure，the translator translates it into an active voice structure by converting the agent“burning of fuel”into a subject．
⑤The original passive-voice sentence is translated into an active-voice sentence by converting the agent of the action“steam turbine generators”into the subject of the Chinese sentence，while the subject of the original sentence“the mechanical energy”is converted into the object of the predicate verb in the Chinese sentence．
A current search of the files indicates that the letter is no longer in this bureau’s possession．①It is noted that②the letter was received two months ago，and after study，③returned to your office．In view of the foregoing，④it is regretted that your office has no record of its receipt．If⑤the letter is found，⑥it would be appreciated if this bureau⑦was notified at once．
最近查找了卷宗，发现本局并无此信。①根据记录，②信是两个月前收到的，经研究后，已③寄还贵处。有鉴于此，贵处似无收信的记录，④甚为遗憾。如能⑤找到此信，请立即⑦通知本局，⑥不胜感谢。
Notes: This is a letter in which there are several passive sentences．The translation completely follows the Chinese language writing style and features so that it is very fluent and natural when reading．